Process for producing a photographic light sensitive element

ABSTRACT

PHOTOGRAPHIC ELEMENTS WITH INCREASED VICOSITY OF GELATIN LAYERS CONTAINING AN ACID DYE AND A MORDANT FOR THE DYE ARE OBTAINED BY INCORPORATING IN THE GELATIN LAYER A COPOLYMER OF 30 TO 70 MOLE PERCENT   -CH2-C(-R)(-CO-NH2)-   R=H OR CH3, AND   -CH2-C(-R)(-COO-M)-   R=H OR CH3 M=H, NH4, LI, NA OR K. THE COPOLYMER HAS A DEGREE OF POLYMERIZATION OF 1,500 TO 50,000. A PROCESS FOR INCREASING THE VICOSITY OF GELATIN/ACID DYE/MORDANT LAYER COMPRISING ADDING SUCH A COPOLYMER THERETO. AN IMPROVED COATING PROCESS USING A COPOLYMER.

United States Patent US. Cl. 96-84 A Claims ABSTRACT OF THE DISCLOSURE Photographic elements with increased viscosity of gelatin layers containing an acid dye and a mordant for the dye are obtained by incorporating in the gelatin layer a copolymer of 30 to 70 mole percent R=H or CH and CHg-C- COOM R=H or CH,

M=H, NH Li, Na or K. The copolymer has a degree of polymerization of 1,500 to 50,000. A process for increasing the viscosity of gelatin/acid dye/mordant layer comprising adding such a copolymer thereto. An improved coating process using such a copolymer.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to a process for producing photographic light-sensitive silver halide elements and, in more detail, to a process for producing a photographic light-sensitive silver halide element using a gelatin coating solution comprising an acid dye, a mordant and a substance which increases the viscosity of the coating solution without lowering the mordanting effect of the mordant.

(2) Description of the prior art In general, photographic light-sensitive silver halide elements are composed of a light-sensitive silver halide emulsion layer on a support such as a cellulose triacetate film, a polyethylene terephthalate film, a resin coated paper or a baryta paper. If desired, non-light-sensitive auxiliary layers can be present such as antihalation layers, intermediate layers, yellow filter layers, protective layers, etc. as are known to the art.

These non-light-sensitive auxiliary layers contain a binder such as gelatin as the main ingredient and, if desired, various dyes.

To form an element comprising a plurality of layers it will be obvious that higher production can be achieved with increased coating speed in the preparation thereof. Many kinds of processes have been proposed to achieve such a result.

3,746,547 Patented July 17, 1973 ice For example, in the process of coating which comprises dipping a support once into a photographic coating solution in a container and raising while running, the airknife coating method is known in which the excess coating solution is taken off by blowing high speed air onto the coated surface. In this case, it is necessary to increase the viscosity of the coating solution (to increase the rate of gelatin) and to increase the strength of the gel so as not to disturb the uniformity of the coating film by air pressure.

Further, there is known a method which comprises applying the coating solution thinly to a moving support by simultaneously pouring a plurality of coating solutions onto an inclined surface which contacts the support, or by extruding the coating solutions onto the support from a slit. In such cases, it is also necessary to increase the viscosity of the coating solutions so that the coating solutions can be applied in laminar flow without mixing coated layers.

Viscosity increase can thus be seen to be important in the above processes. If the viscosity of the coating solutions is low, the following disadvantages are encountered: (1) It becomes impossible to apply the components to be coated, since substances having a large specific gravity in the coating solution precipitate upon standing. If stirred vigorously to prevent such precipitation, bubbles form and uniformity of the coated film is injured. (2) Gelation caused by a cool air stream just after application is very slow, and the resulting gel becomes weak, whereby uniformity of the coating film is injured.

In these circumstances, it is necessary to increase the viscosity of the coating solutions, and many attempts for solving the problem have been proposed. For example, there is one method for increasing the viscosity by increasing the gelatin concentration in the coating solutions. However, this method brings about a lowering in sharpness of the photographic images because the ratio of gelatin to dyes increases, and the thickness of the film increases to obtain the desired density. Further, it has been disclosed in German patent specification No. 912,- 778 that the viscosity of a coating solution can be increased by adding water-soluble high molecular weight substances containing sulfonic acid groups to the coating solution. In this case, thickness of the dry film hardly increases. However, these high molecular weight substances have the following faults. In the case of gelatin coating solutions containing acid dyes having an acid group basic mordants as shown in US. patent specifications No. 2,839,401 and No. 3,445,231, if the high molecular :Wei-ght substances as described above are used to increase the viscosity, the mordanting effect of the mordants lowers to remarkably increase diffusion of the dyes into adjacent layers. For example, a yellow dye in the yellow filter layer dilfuses into an adjacent blue-sensitive emulsion layer to cause desensitization. Further, in the case of preserving the coating solution at room temperature, viscosity increases by the lapse of time to impede application.

SUMMARY OF THE INVENTION One object of the present invention is to provide a method of increasing the viscosity of a gelatin coating solution containing an acid dye and a mordant which does not have the above-mentioned faults.

Another object is to provide a process for producing a photographic light-sensitive silver halide element using a coating solution which has increased viscosity without any harmful influence upon the properties of the gelatin coating solution.

These and other objects are attained by adding a copolymer having degree of polymerization of 1,500'-50,000 which comprises from about 30 to about 70 mole percent of recurring units represented by the formula:

(wherein R is H or CH wherein remainder of the copolymer molecule comprises recurring units represented by the formula:

(wherein R is H or CH and M is H, NH Li, Na or K), to a gelatin coating solution containing an acid dye and a mordant therefor.

DETAILED DESCRIPTION OF THE INVENTION We have found that the ratio of acrylamide (or methacrylamide) and acrylic acid (or methacrylic acid) as the monomer component in the above-mentioned copolymers and the degreee of polymerization of the copolymers are factors which have an important influence upon the characteristics of the copolymers and those having monomer molar ratio of 3:7-723 and a degree of polymerization of 1,50050,000 are most preferably used. This corresponds to a molecular weight of approximately about 100,000 to about 3,500,000.

If the acrylamide (or methacrylamide) component in the copolymer exceeds 70 mol percent the copolymer has poor compatibility with gelatin and causes phase separation between the copolymer and the gelatin. Consequently, not only is transparency of the coating film injured and insoluble matters formed in the coating film, but also the desired viscosity increasing effect can not be sufficiently obtained.

On the other hand, if the acrylic acid (or methacrylic acid) component exceeds 70 mol percent, the influence of the carboxyl group of the acrylic or methacrylic acid grows large enough to cause a reciprocal action between the mordant (the basic polymer), i.e., the copolymer easily coaguulates due to an electrostatic interaction between the viscosity increasing, agent and mordant, and consequently the polymers precipitate. Furthermore, an acid excess effects adsorption between the mordant and the acid dye to result in a lowering of the essential mordanting eifect.

So far as the object is to increase viscosity, it is naturally preferred that the molecular weight of the copolymer be higher. The molecular weight must be at least about 100,000. However, when the molecular weight is beyond about 3,500,000, compatibility with gelatin cannot be obtained even though controlling the ratio of monomer components. This phenomenon is especially observed in the film state (after drying) as compared to the solution state. Accordingly, unless this molecular weight range is observed it is difficult to obtain a transparent flat coating film having excellent physical-mechanical properties suitable for practical use. A particularly preferred range of molecular weights is from 500,000 to 2,500,000,

Examples of the copolymers used in the present invention are shown below:

These copolymers can be synthesized by hydrolyzing polyacrylamide or by copolymerizing acrylamide (or methacrylamide) and acrylic acid (or methacrylic acid). Synthesis examples are shown below.

Synthesis 1 The copolymers of the present invention per se and the synthesis thereof are well known. The terminal groups are not material to the present invention as with many cases wherein vinyl-type polymers are used.

500 g. of acrylamide, 3.6 liter of water, 5.0 ml. of triethanolamine and 1.2 g. of potassium persulfate as polymerization initiator were charged into a 5 liter reactor. After substituting nitrogen for the atmosphere in the vessel, the temperature was elevated to 40 C. with stirring.

Stirring was stopped 20 minutes after the beginning of reaction, since the viscosity of the reactors increased gradually, and the mixture was subjected to polymerization by permitting the mixture to stand for 2 hours. Ap-

proximately 20 ml. of the resulting polyacrylamide was sampled and the viscosity determined after purification. The result was which corresponds to ca. 2,000,000 molecular weight. The resulting polyacrylamide was then hydrolyzed by stirring at 70 C. with adding 200 g. of potassium hydroxide and 1 liter of water thereto. After reacting for 2 hours, the resulting acrylamide-potassium acrylate copolymer was washed 3 times With 5 liter of methanol. The resulting white polymer was dried at 50 C. in a vacuum for one week. 650 g. of the polymer was obtained, the viscosity of which was [1 ]=9.35 at 30 C. in a 1% aqueous sodium chloride solution.

Synthesis 2 86.4 g. (1.2 moles) of acrylic acid, 56.8 g. (0.8 mole) of acrylamide, 800 m1. of water and 420 mg. of potassium persulfate as the polymerization initiator were charged into a 2 liter reactor. After substituting nitrogen for the atmosphere in the vessel the mixture was stirred at 70 C. for minutes. The resulting copolymer was put into a dialysis membrane unit and dialyzed with distilled water for one night. The copolymer was then subjected to freeze-drying. Yield: g. (95.2%

[ 11%. N-cr 7- The molecular weight was approximately 100,000.

It is possible to increase the viscosity of gelatin coating solutions containing acid dyes and mordants by adding the copolymer of the present invention without lowering the mordanting effect of the mordant. Accordingly, the copolymer is very useful as a viscosity increasing agent for coating solutions which are used for forming colored gelatin layers such as yellow-filter layers, antihalation layers, etc. Further, by the addition of the viscosity increasing agent the ease of spinning the coating solution is improved and consequently cut of running or interruption of the solution to form an uncoated area at application is prevented. Moreover, there is no disadvantage that the spectral sensitizing dyes are desorbed from silver halide particles as with the known sodium polystyrene sulfate material or that the viscosity of the coating solution gradually increases during the lapse of time.

is from about 1% to about 8% by weight based on the gelatin weight. It is not preferred that the amount be tion include any basic mordant which is a high molecular weight compound, including for example, polymers containing amino or ammonium groups, polymers containing heterocyclic nitrogen containing rings and polymers containing phosphonium groups.

too large, because drying of the coating film is slowed 5 In short, the present invention finds broad application and the film is soft and sticky. The viscosity of the coat with acid dyes and basic mordants as are commonly ing solution depends upon the composition of the coating known in the photographic art. Suitable dyes, and morsolution and the pr p i pc y, l P p dants are described e.g., in US patent specifications No. f and amount of the Y lflcl'e aslng agent- 10 3,316,091 and No. 3,423,207, British patent specifications PP afnount can be detefmlned 3! y a No. 1,034,044 and No. 1,142,697, German patent specifillmlnal'y p 1 d b cations No. 1,472,789 and No. 1,547,999, French patent f ig i? g l l .2 specifications No. 1,421,679 and No. 1,477,002, Belgian cosity of from about 10 to about 100 centipoises, especial- German ofienkigungsschnft 9 addltlon to o the above-mentioned US. patent specifications. 1y 15 to centrpoises at 38 C.

The acid dyes that can be used in the present invention In h fonfjwmg the Pmsent mventlon 1S explamed include any filter dye that has one or more acidic groups f detall by examplfsi examples are such as sulfo or carboxyl groups, including for example, i Intended to P llmltatlve 0f the lflventlonstyryl dyes, oxonol dyes, cyanine dyes, merocyanine dyes, 20 In the following examples the acid dyes, mordants and azo dyes and triphenylmethane dyes. viscosity increasing agents used for comparison had the The mordants that can be used in the present invenfollowing formulae:

Dye 1 H;C-CCH-CH=CC| -CH3 (Ye1low.)

l l SOIK SOtK Dye 2 Do.

H;C(H3-C=CH--N(CH:)z

D Dye NaOaS-N=NH(|3--fi)-C 0 ONE O=C N SOaNa Dye 4 HOOCCCHCH=CH-CH=C C-COOH (Magenta.)

SO K SO K Dye 5 H;C-CFHCHr-CHCH=F-CH1 Do.

i k G=0 0=c\ N N SOIK Dyed HOCCCHCH=CH-OH=CHCH=C-C*COOH (Cyan.)

SOIK SO;K

Dye 7 S (Yellow.)

C=b =S M Ida t 1 (=1 000) viscosity was again determined. The results are shown in o n oin-019 Table 1.

\ N 2 TABLE 1 I W 1 25 Viscosity increasing agent- Compari- None son (1) -1 -2 -3 -4 -5 -6 Mordantll f it o C T Y T ifit 'fo in n utes zl 6.2 as 24 2o 24 2s 1s 28 N 30 AlterShours 6.5 42 22 24 2a 19 CH; U As shown in Table 1, the viscosity of a gelatin solution (CHZCHQSOF) containing a viscosity increasing agent is higher than that of the solution which does not contain a viscosity mcreasing agent. In the solution containing Comparison Mordanta (nnl'om) viscosity increasing agent (i) the difference in viscosity between after 30 minutes and after 8 hours is very large.

oocnzcrrm On the contrary, in the solutions containing Viscosity m- CH creasing agent-1, -2, -3, -4, -5 and -6 of the present inven- 40 tion the viscosity varies only slightly after 8 hours, which Mordan H means that these viscosity increasing agent are excellent.

T NH The change of viscosity with time in the present inven- C O 0 CH C N tion is usually equal or less than 20% in 8 hours.

EXAMPLE 2 Solutions were prepared by adding 5 ml. of a 5 wt. cmpaflsn percent aqueous solution of Viscosity increasing agent-3 -CH CH gigging in l of the present invention and 8 ml. 04'? a 2 wt. percent aqueagent ous solution of Comparison viscosity increasing agent (i), respectively, to 100 g. of a 5 wt. percent aqueous gelatin solution containing 0.5 g. of Dye-1 and 0.5 g. of Mordant-l to prevent diffusion of the dye. 2,4-dichloros 6-hydroxy-1,3,5-triazine as a hardening agent, sodium d0- decylaminopropionate as a coating aid and citric acid as a %;53555 l (=1O'OOO) pH controlling agent were then added to the resulting s0- lncreaslpg I n lutions to produce two coating solutions. agent COOH A silver iodidobromide emulsion layer containing 1- phenyl-3-dodecylamino-S-pyrazolone as the magenta %253353 l L ("45mm coupler, which was green-sensitized by 3,3',9-triethyl-5,5'- increasin n diphenyl-oxacarbocyanine iodide, was provided on a celluagent lose triacetate support. The above-mentioned two kinds of colored gelatin solutions were applied to this layer and dried. Then, a silver iodide bromide emulsion layer containing 4-dodecylbenzoyl-2-methoxyacetamide as the yellow coupler was applied to the resulting layer. Two EXAMPLE 1 kinds of multilayer light-sensitive elements containing the viscosity increasing agent of the present invention and, a comparison viscosity increasing agent for in the yellow filter layer were thus produced.

These two light-sensitive elements were exposed to light using a NSG-III type sensitometer of 4800 K. as a light source for l/ 20 seconds. The elements were then developed at 24 C. for 10 minutes with a black and white developer having the formulation set out below. The elements were then subjected to washing, hardening, washing, reversal exposing, developing for 15 minutes by a color developer having the formulation described below, washing, bleaching, washing, fixing and washmg.

Black and white developer:

Water to make 1 liter.

In table 2, the relative values of the amount of exposure which affords a positive image having a 1.0 density in the yellow colored blue-sensitive layer are shown as the relative sensitivity, in which the value in the sample cointaining Viscosity increasing agent-3 of the present invention is 100.

TABLE 2 Viscosity increasing agent: Relative sensitivity Viscosity increasing agent for comparison (i) 65 Viscosity increasing agent-3 100 From Table 2, it can be seen that the relative sensitivity of the blue-sensitive emulsion layer of the element containing Viscosity increasing agent-3 of the present invention is higher than that of the element containing Comparison viscosity increasing agent (i). Namely, it is clear that lowering of the sensitivity by diffusion of the dye from the yellow filter layer into the upper blue-sensitive emulsion layer is large using Comparison viscosity increasing agent (i). On the other hand, Viscosity increasing agent-3 of the present invention is not subject to such fault.

EXAMPLE 3 Solutions were prepared by adding 6 g. of wt. percent aqueous solutions of Viscosity increasing agent-2 and -4 of the present invention and Comparison viscosity increasing agent (ii) and (iii), respectively, to 100 g. of a 5 wt. percent aqueous gelatin solution containing 0.5 g. of Dye-1 and 0.5 g. of Mordant-l to prevent diffusion of the dye. 2,4-dichloro-6-hydroxy-1,3,5-triazine as the hardening agent, sodium dodecylaminopropionate as the coating aid and citric acid as the pH controlling agent were then added to the resulting solutions to produce 4 coating solutions.

When these coating solutions were applied after standing for 10 hours with stirring at 40 C., the coated film containing Comparison viscosity increasing agent (ii) had a mat sunface because the dye and the mordant coagulated in the coating solution. In the coating solution containing Comparison viscosity increasing agent (iii), the viscosity increasing agent had bad compatibility with gelatin and did not dissolve uniformly. On the contrary, in the coating solutions containing Viscosity increasing agent-2 and -4 of the present invention, uniform dissolution occurred and coagulation of the dye and the mordant did not come about. Consequently the state of the surface of the coating film was excellent.

EXAMPLE 4 This example illustrates that a mat surface on the coating film which is brought about by coagulation of the dye and the mordant does not form when using the viscosity increasing agent of the present invention with varying (1 es.

5 g. kinds of coating solution were prepared by adding 6 g. of a 5 wt. percent aqueous solution of Viscosity increasing agent-3 of the present invention to solutions composed of g. of a 5 wt. percent aqueous gelatin solution, 0.5 g. of Dye-2,-3,-4,-5 and -7, respectively, and 0.5 g. of Mordant-Z, and then adding a hardening agent, a coating aid and a pH controlling agent thereto.

When these 5 coating solutions were applied (after standing for 10 hours while stirring at 40 C.,) to a support, coagulation of the dyes and the mordants do not occur, and the state of the coating film surface was excellent from all of the coating solutions.

EXAMPLE 5 Coating solutions were prepared by adding 6 g. Olf a 5 wt. percent aqueous solution of Viscosity increasing agent-3 of the present invention to solutions composed of 100 g. of a 5 wt. percent aqueous gelatin solution, 0.2 g. of Dye-1, -5 and -6, respectively, and 0.6 g. of Mordant-2 to prevent diffusion of the dyes, a hardening agent, a coating aid and a pH controlling agent were added thereto.

When these coating solutions were applied (after standing for 10 hours while stirring at 40 C.), coagulation of the dyes and the mordants did not occur and the state of the coating film surface was excellent.

EXAMPLE 6 This example illustrates that a mat surface of the coating film which is brought about by coagulation of dyes and mordants does not form when using the viscosity increasing agents of the present invention with varying mordants.

8 kinds of coating solutions were prepared by adding 0.5 g. of Dye-1 and 0.5 g. of Mordant-l, -2, -3 and -4, respectively, to 100 g. of 5 wt. percent aqueous gelatin solutions, and then adding 6 g. of 5 wt. percent aqueous solution of Viscosity increasing agent-2 of the present invention and 8 g. of a 2 wt. percent aqueous solution of Comparison viscosity increasing agent (i), respectively.

After adding a hardening agent, a coating aid and a pH controlling agent, the solutions were applied to a cellulose triacetate support so as to form a film having a 2 t dry thickness. To the resulting layer, a silver halide emulsion containing a yellow coupler as described in Example 2 was applied so as to form a film having a 5 1. thickness. The elements were dried to produce 8 kinds of sensitive ele. ments. These sensitive elements were exposed and developed as in Example 2.

In Table 3, the relative values of the amount of exposure which affords a yellow positive image having a 1.0 density are shown as relative sensitivities, in which the value in the sample containing Viscosity increasing agent-2 of the present invention is 100.

It is clear from Table 3 that the relative sensitivity obtained by Viscosity increasing agent-2 of the present invention is higher in use with any mordant, and that the diffusion of dyes into the blue-sensitive emulsion layer is less as compared with using Comparison viscosity increasing agent (i).

What is claimed is:

1. In the process of producing a photographic light-sensitive element including the step of coating a support with a. silver halide emulsion layer the step of adding a copolymer comprising 30 to 70 mole percent of recurring units represented by the formula (wherein R is H or CH the remainder of the copolymer molecule comprising recurring units represented by the formula (wherein R is H or CH; and M is N, NH Li Na or K), said copolymer having a degree of polymerization of 1,500 to 50,000 to a gelatin coating solution containing an acid dye and a polymeric basic mordant for the dye, whereby the viscosity of the coating solution increases Without reducing the mordanting eiTect of the mordant.

2. The process according to claim 1, wherein the viscosity of the resultant gelatin solution is between about and about 100 centipoises at 38 C.

3. In the process for producing a photographic lightsensitive element including the step of coating a support with a silver halide emulsion layer the step of adding a copolymer comprising 30 to 70 mole percent of acrylamide or methacrylamide, the remainder of the copolymer molecule comprising acrylic acid, methacrylic acid or an ammonium, lithium, sodium or potassium salt thereof, said copolymer having a degree of polymerization of 1,500 to 50,000 to a gelatin coating solution containing an acid dye and a polymeric basic mordant for the dye, whereby the viscosity of the coating solution increases without reducing the mordanting elfect of the mordant.

4. In a photographic light-sensitive element comprising a support, a silver halide emulsion layer and a gelatin layer containing an acid dye and a polymeric basic mordant for the dye, the improvement wherein said gelatin layer contains a copolymer comprising 30 to mole percent recurring units represented by the formula (wherein R is H or CH the remainder of the copolymer molecule comprising units represented by the formula (wherein R is H or CH, and M is H, NH Li Na or K), said copolymer having a degree of polymerization of 1,500 to 50,000.

5. In a photographic light-sensitive element comprising a support, a silver halide emulsion layer and a gelatin layer containing an acid dye and a polymeric basic mordant for the dye, the improvement wherein said gelatin layer contains a copolymer comprising 30 to 70 mole percent of acrylamide or methacrylamide, the remainder of the copolymer molecule comprising acrylic acid, methacrylic acid or an ammonium, lithium, sodium or potassium salt thereof said copolymer having a degree of polymerization of 1,500 to 50.000.

References Cited UNITED STATES PATENTS 3,615,545 10/1971 Kalenda 96-84 A RONALD H. SMITH, Primary Examiner US. Cl. X.R. 

